The connection between Napoli Sotterranea and the Campi Flegrei

Beneath the bustling streets of Naples lies a mysterious underground world, an intricate system of passages and tunnels that form a path 40 metres deep. This, and much more, is Napoli Sotterranea. But perhaps not everyone knows that the network of tunnels is the result of millennia of volcanic eruptions that have shaped the city and its history. But what makes this place even more fascinating? Its origin is linked to one of the largest volcanic eruptions in the Mediterranean: the eruption of the Campi Flegrei.

Volcanic origins of Napoli Sotterranea

The material that forms the Napoli Sotterranea is not just any rock. It is volcanic tuff, the product of some of the most violent eruptions ever recorded in the Mediterranean basin. An extraordinary example is the eruption of the Campi Flegrei caldera some 39,000 years ago, known as the Campania ignimbrite eruption. This eruption was so devastating that its ashes have been found from the Tyrrhenian Sea as far as Russia, covering vast areas with layers of pyroclastic material.

The eruption had global effects, with climate disruptions spreading around the world. During the eruption, as much as 67 km³ of magma was emitted, an enormously greater quantity than that of the famous eruption of Vesuvius in 79 A.D., which buried Pompeii and Herculaneum (about 6-8 km³ of magma). More than two thirds of Campania were covered by a thick layer of volcanic tuff. But to this eruption we must also add a second one – dating back some 15,000 years – better known as the ‘eruption of the Neapolitan yellow tuff’, which added more tuff on top of that already deposited. In short, without these two events of nature – which formed an impressive layer of rock – it would not have been possible to excavate the underground passages of Naples.

History and evolution of Naples Underground

The actual creation of underground passages in Naples began around the 3rd century BC with the Greeks. The tuffaceous rock was soft enough to be easily excavated and used to construct buildings and structures. The Greeks exploited this raw material to develop their construction system, but it was the Romans who made massive use of the underground network.

During the Roman occupation, Naples saw the construction of an important network of underground aqueducts that supplied drinking water to the city’s fountains and homes. These aqueducts were supplied via underground tunnels, some of which are still visible today, with traces of hydraulic plaster testifying to the advanced techniques used by the Romans to make the conduits waterproof.

Visit Napoli Sotterranea: a journey into the heart of history

To this day, Napoli Sotterranea is one of the city’s most fascinating tourist attractions, allowing visitors to discover the hidden side of the city and explore a network of passages that tell millennia of history. From its volcanic origin to its function as a refuge during World War II, this underground labyrinth bears witness to the transformations and vicissitudes that have marked Naples over the centuries.